Strapping machine

ABSTRACT

A machine for tensioning a strap around an object includes a pair of toothed gripping jaws movable by first drive means into and out of holding engagement with the strap in directions substantially normal thereto to prevent scoring thereof, the gripping jaws being pivotally movable to a releasing position for accommodating removal of the strap therefrom, sealing jaws and a seal feed member respectively movable by second and third drive means alternately into ea sealing region, the seal feed member in the sealing region positioning a seal therein and guiding the passage of the strap therethrough, the sealing jaws in the sealing region sequentially deforming the seal into partial sealing and full sealing engagement with the strap, straightening means movable by fourth drive means into and out of straightening engagement with the supply portion of the strap, and control circuitry for controlling the operation of the several drive means.

Elite States Patent Plattner et al.

[451 Aug. 29, 1972 [54] STRAPPING MACHINE [73] Assignee: Interlake, Inc., Chicago, Ill.

Great Britain 100/ 30 Primary Examiner-Billy I. Wilhite Attorney-Prangley, Clayton, Mullin, Dithmar & Vogel [57] ABSTRACT A machine for tensioning a strap around an object includes a pair of toothed gripping jaws movable by first drive means into and out of holding engagement with the strap in directions substantially normal thereto to prevent scoring thereof, the gripping jaws being pivotally movable to a releasing position for accommodating removal of the strap therefrom, sealing jaws and a seal feed member respectively movable by second and third drive means alternately into ea sealing region, the-seal feed member in the sealing region positioning a seal therein and guiding the passage of the strap therethrough, the sealing jaws in the sealing region sequentially deforming the seal into partial sealing and full sealing engagement with the strap, straightening means movable by fourth drive means into and out of straightening engagement with the supply portion of the strap, and control circuitry for controlling the operation of the several drive'means.

39 Claims, 19 Drawing Figures PlTENTEflwszsmz SHEET [31!]! 11 l v 8T t Fla.)

//v VENTORS ROBERT F. PLATTNER FRANK c. WELLER ED WARD STARON PATENTEDM 29 SHEET DZUF 11 rmemsnkuszs 1912 3587.059

SHEET 0311f 11 FIG 5 262 PATENTEDmszs m2 SHEET U l 0F 11 mm Mm PATENTED M122 m2 3.681.059

' SHEEI USUF 11 rmminwszsmz 3.687.059

- sum near 11 minimum m2 3. 687 059 SHEEI 07 0F 11 FIGJO PATENTED M1829 m2 SHEU 08 0F 11 FIGJ? FIG. I8.

347 359 345i 357 E 343 E 358 344 V e; 53fi SEAL 355 356 SEA E STRAP PA SEAL L 35/ F TE IVS/0N SEAL a FEED 8 EEO =123R/P QETRACT FEED TRAIGHT J 352 I I 4/ g m\3 I I/I 360 33/ 334 335 SOURCE 333 332 336 PATENTED M1829 I972 SHEET OSUF 11 STRAPPING MACHINE This invention relates to strapping machines for applying flexible straps about packages or other objects to be bound. More particularly, this invention relates to improvements in strapping machines of the general type disclosed in U. S. Pat. No. 3,139,813 issued July 7, 1964, to Marchand B. Hall et al., the disclosure of which patent is incorporated herein by reference.

It is an important object of this invention to provide a strapping machine for applying a length of strap around an object, the strapping machine comprising first and second gripping members having gripping surfaces thereon and being movable between a feeding condition and a gripping condition, the gripping members in the feeding condition thereof being spaced apart for accommodating the free passage of the leading end of the strap therebetween for forming a loop around the object with the leading end of the strap overlapping the supply portion thereof, the gripping members in the gripping condition thereof cooperating for securely clamping the leading end of the strap therebetween with the gripping surfaces respectively in engagement with the opposite sides of the leading end of the strap, drive mechanism coupled to the gripping members for effecting movement thereof between the feeding condition and the gripping condition thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, and joint forming means for forming a joint between the overlapped portions of the tensioned strap to secure the strap about the object, the drive mechanism effecting movement of the gripping members in a direction substantially normal to the plane of the adjacent portion of the strap just prior to contact therewith to prevent scoring thereof by the gripping surfaces, whereby the gripping members securely hold the leading end of the strap without scoring and resultant weakening thereof.

It is a further object of this invention to provide a strapping machine of a type set forth, wherein a first one of the gripping members is stationary and a second one of the gripping members is movable with respect to the first gripping member and is provided with gripping teeth thereon, the second gripping member being movable among the feeding condition and the gripping condition and a releasing condition disposed intermediate the feeding condition and the gripping condition, the drive mechanism effecting initial movement of the second gripping member away from the gripping condition thereof in a second direction opposite to the first direction.

It is another object of this invention to provide a strapping machine of the type set forth, wherein the second gripping member is movable to first and second releasing conditions, the second gripping member in the first releasing condition thereof being disposed intermediate the feeding condition and the gripping condition and abutting against the strapped object, the second gripping member in the second releasing condition thereof abutting the strapped object laterally of the strap and out of engagement therewith for accommodating release of the sealed strap from the gripping members, the drive mechanism effecting pivotal movement of the second gripping member from the first releasing condition to the second releasing condition thereof along the strapped object.

Another object of this invention is to provide a drive mechanism includes bias means urging the second gripping member toward the feeding condition thereof, and a drive assembly coupled to the second gripping member and operable to first and second actu ated conditions and cooperating with the bias means for effecting movement of the second gripping member among the feeding and gripping and first and second releasing conditions thereof.

Yet another object of this invention is to provide a strapping machine for applying a length of strap'around an object, the strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portions of the strap for holding a seal therein and a withdrawn deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of the sealing region, and drive mechanism coupled to the seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, the drive mechanism being coupled to the sealing jaws for effecting movement thereof between the sealing position and the retracted position thereof, the drive mechanism alternately placing the seal feed member and the sealing jaws in the sealing region without interference one with the other, whereby the seal feed member and the sealing jaws cooperate to place a sealin sealing engage ment with the overlapped portions of the strap to form the seal joint therebetween.

In connection with the foregoing object, it is another object of this invention to provide a strapping machine of the type set forth wherein the sealing jaws have camming surfaces thereon and are spaced apart a distance greater than the width of the seal, and further including cam members respectively disposed for camming engagement with the camming surfaces of the sealing jaws and cooperating therewith and with the drive mechanism for effecting movement of the sealing jaws in a direction substantially normal to the plane of the adjacent portion of the strap during the first portion of the movement of the sealing jaws from the retracted position to the sealing position thereof and for effecting pivotal movement of the sealing jaws into engagement with the seal during the last portion of the movement of the sealing jaws from the retracted position to'the sealing position thereof.

it is another object of this invention to provide a strapping machine of the type set forth, which includes first drive mechanism coupled to the seal feed member for effecting movement thereof, second drive mechanism coupled to the sealing jaws for effecting movement thereof, and control apparatus coupled to the first and second drive mechanisms for controlling the operation thereof.

It is another object of this invention to provide a strapping machine of this type set forth, wherein the 3 sealing jaws are movable in the sealing region between a partial sealing position and a full sealing position, the second drive mechanism effecting movement of the sealing jaws between the retracted position and the partial sealing position thereof, and further including a third drive mechanism coupled to the sealing jaws and to the control apparatus for effecting movement thereof between the partial sealing position and the full sealing position thereof, the control apparatus effecting movement of the sealing jaws into the partial sealing position thereof prior to operation of the tensioning means and effectingmovement of the sealing jaws into the full sealing position thereof after operation of the tensioning means.

It is another object of this invention to provide a strapping machine of the type set forth, which further includes a die member movable between a sealing position in the sealing region for crimping the side edges of the seal and the strap for facilitating the formation of the seal joint therebetween and a retracted position out of the sealing region, the drive mechanism being coupled to the die member for effecting simultaneous movement of the sealing jaws and the die member. I

It is still another object of this invention to provide a strapping machine for applying a length of strap around an object, the strapping machine comprising means for feeding the strap in a loop around the object with the leading end of the strap overlapping the supply portion thereof, gripping means for securely gripping the leading end of the strap, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, and joint forming means for forming a joint between the overlapped portions of the tensioned strap to secure the strap about the object, strap straightening means disposed adjacent to the feeding means and movable between a straightening configuration and a retracted configuration, the straightening means in the straightening configuration thereof engaging the supply portion of the strap for effecting the straightening thereof, the straightening means in the retracted configuration thereof being disposed out of engagement with the strap for accommodating free movement thereof, and drive means coupled to the straightening means for effecting movement thereof to the straightening configuration thereof during the operation of the feeding means and effecting movement thereof to the retracted configuration thereof during operation of the tensioning means, whereby the straightening means serves to straighten the strap without impeding the tensioning thereof.

' Further features of the invention pertain to the particular arrangement of the parts of the strapping machine whereby the above-outlined and additional operating featuresv thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. I is a perspective view on a reduced scale of a bundle of objects after having had straps applied thereto by the strapping machine according to the present invention;

FIG. 2 is a front elevational view of a strapping machine constructed in accordance with and embodying the features of the present invention, indicating the orientation of the strapping machine with respect to an object to be strapped;

FIG. 3 is an enlarged fragmentary side elevational view of the strapping machine illustrated in FIG. 2, as viewed from the right-hand side thereof; v

FIG. 4 is a further enlarged view in vertical section taken along the line 4-4 in FIG. 3, and illustrating the seal feed bar in its feeding position;

FIG. 5 is a view in vertical section taken along line 5-5 in FIG. 4, and illustrating the strap guide assembly;

FIG. 6 is a view in vertical section taken along line 6-6 in FIG. 4, and illustrating further details of the strap guide assembly; v

. FIG. 7 is a reduced bottom plan view of the strapping machine illustrated in FIG. 2;

FIG. 8 is an enlarged view in vertical section taken along the line 8-8 in FIG. 2, and illustrating the holding jaw drive assembly of the present invention;-

FIG. 9 is an enlarged view in vertical section taken along the line 99 in FIG. 2, and illustrating the sealing jaw drive assembly of the present invention;

FIG 10 is a further enlarged fragmentary view in partial section of the holding jaws and drive assembly therefor illustrated in FIG. 8, with portions of the holding jaw assembly broken away to illustrate the internal details thereof, and further illustrating the various positions of the holding jaw assembly;

FIG. 11 is a further enlarged fragmentary view of the sealing jaws and drive assembly therefor illustrated in FIG. 9, with portions of the sealing jaw assembly broken away to illustrate the internal details thereof, and further showing the various positions of the sealing jaw assembly;

FIG. 12 is a diagrammatic view of the sealing jaws in the retracted and open position thereof, illustrating their orientation with respect to the seal;

FIG. 13 .is a diagrammatic view similar to FIG. 12, and illustrating the sealing jaws in the partial sealing position thereof;

FIG. 14 is a diagrammatic view similar to FIGS. 12 and I3, and'illustrating the sealing jaws in the fullsealing position thereof;

FIG. 15 is a fragmentary view in horizontal section taken along the line 15-15 in FIG. 11, and illustrating the holding jaws and the sealing jaws in the fully closed positions thereof;

FIG. 16 is a fragmentary view in a horizontal section taken along the line 16-16 in FIG. 11, and illustrating the holding jaws and sealing jaws in the fully closed positions thereof;

FIG. 17 is a fragmentary side elevational view in partial section of the strapping machine of the present invention, as viewed from the left-hand side of FIG. 2;

FIG. 18 is a schematic circuit diagram of the pneumatic control circuit for the strapping machine of the present invention; and

FIG. 19 is a schematic circuit diagram of the electric control circuit for the strapping machine of the present invention.

Referring now to the drawings and, in particular, to I FIGS. 1 to 3 thereof, there is illustrated a strapping machine, generally designated by the numeral 50, constructed in accordance with and embodying the features of the present invention. The strapping machine 50 includes a strapping head 55 to be utilized for tensioning and sealing a length of flexible strap 40 about an object 48. The strapping machine 50 is useful for applying straps about any of numerous types of objects or groups of objects. FIG. 1 illustrates a package 48 of objects 49 .which may typically be boards, bricks, etc. which have been securely strapped together by the strapping machine 50 of this invention. In use, the object 48 is placed into a strapping location 46 adjacent to the strapping head 55, which strapping location will normally be surrounded by a strap guide track (not shown) for guiding the strap web 40 about the object 48. Suitable conveyor apparatus may also by provided for delivering the object 48 to and from the strapping location 46, all as is more fully disclosed in the aforementioned U. S. Pat. No. 3,139,813. While, in the preferred embodiment, the strapping head 55 has been shown overlying the strapping location 46, it will be appreciated that other orientations of the strapping head 55 with respect to the strapping location 46 may be utilized.

The strapping machine 50 is suitably supported upon a support frame 42 and includes a main support plate 44 on which are mounted the strapping head 55 and a strap drive assembly housing 60. The housing 60 includes an inner plate 61 having a part-cylindrical hood flange extending outwardly therefrom along the upper end thereof. Secured to the hood flange 62 and extending downwardly and rearwardly therefrom substantially parallel to the inner plate 61 is an oblong outer plate 63. Mounted in horizontally aligned pairs of openings in the inner and outer plates 61 and 63 are a pair of upper ball bearings 64 and a pair of lower ball bearings 66. Rotatably mounted in the lower ball bearings 66 are two stub shafts 67 of a pair of eccentric shaft support arms 65, which are disposed substantially parallel to each other and spaced apart a predetermined distance.

A relatively small diameter rotary feed wheel 70 is mounted within the housing 60 for rotation about a shaft 71 journaled in the upper ball bearings 64, the rotary feed wheel 70 being provided with a serrated or toothed annular outer surface 74 extending circumferentially therearound. The shaft 71 is rotatably driven by a reversible air motor 72 secured to the inner plate 61 of the housing 60 by suitable fastening means. A relatively large diameter idler wheel 75 is also disposed in the housing 60 and is provided with a hub 78 rotatably mounted by means of ball bearing 79 on a shaft 77 supported between the support arms 65 rearwardly of the stub shafts 67 and substantially parallel to the axis thereof. The idler wheel 75 is provided with a serrated or toothed annular outer surface 76 thereon disposed for tangential engagement with the serrated surface 74 on the feed wheel 70 for frictionally feeding the strap web 40 therebetween.

Coupled to the shaft 77 and extending radially downwardly and rearwardly therefrom is an actuator arm 80 carrying an actuator member 81 at the outer end thereof for engagement with the switch lever 82 of a limit switch LS3 mounted on the support plate 54, the actuating member 81 serving to move the switch lever 82 between the open and closed switch positions thereof in response to rotational movement of the actuating arm 80 about the shaft 77. Extending outwardly from the inner housing plate 61 adjacent to the lower end thereof is a spacer 87 supporting at the outer end thereof a pair of elongated spaced-apart strap guide members. 86, which terminate at a rearward end adjacent to the strapping head 55, and which are preferably resiliently urged to the guiding configuration illustrated in FIG. 17. Extending along the periphery of the idler wheel 75 from the feed wheel to the guide members 86 is an arcuate strap guide 89 mounted on the 'main support plate 44 by suitable means. The armate guide member 89 cooperates with the serrated surface 76 of the idler wheel and with the guide members 86 for guiding the leading end of the strap web 40 along a path from a supply thereof, between the guide members 86, and to the strapping head 55. More particularly, the strap web 40 is normally fed from a coil supply thereof with the leading end 42 of the strap web 40 being threaded between the serrated surfaces 74 and 76 of the feed wheel 70 and idler wheel 75, respectively. The serrated surfaces 74 and 76 cooperate to frictionally grip the strap web 40 therebetween and feed the strap web 40 in a counterclockwise direction, as viewed in' FIG. 2, about the idler wheel 75 in response to a clockwise rotation of the drive wheel 70 by the air motor 72, all in a well known manner. The leading end 42 of the strap web 40 is then guided along the guide members 89 and 86 to the strapping head 55.

Pivotally mounted on a mounting bracket 84 secured to the inner housing plate 61, is a generally L-shaped lever 83, the lower end of the lever 83 extending into the strap path adjacent to the strapping head 55 for engagement by the leading end of the strap web 40 as it reenters the strapping head 55 after being looped around the object 48. The other end of the lever 83 is coupled to the actuator arm 85 of a limit switch LS4 for movement of the switch LS4 between its open and closed conditions in response to movement of the lever 83 by the strap web 40.

As is illustrated in FIG. 2, the strapping head 55 comprises a straightening section 56, a gripping and tensioning section 57, a sealing and shearing section 58 and a seal feed section 59, the strap web 40 being fed through each of these sections of the strapping head 55 by the feed wheel 70, as described above. In the straightening section 56 the strap guide 86 is provided with an arcuate concave straightening surface 88. Mounted on the mounting support plate 54 by suitable means and disposed substantially normal thereto is a side plate 96, an air-actuated straightening piston 90 being mounted on the side plate 96 by means of an angular mounting bracket 91. The piston 90 is provided with a piston rod carrying at the distal end thereof a clevis bracket 94 having a free-wheeling roll 95 rotatably mounted thereon. In use the circumferential surface of the roll 95 is disposed immediately opposite the straightening surface 88 on the guide member 86, the piston rod being adapted for reciprocating movement between a retracted position, illustrated in FIG. 2, wherein the roll 95 is spaced a predetermined distance upwardly from the straightening surface 88 out of engagement with the strap web 40, and a straightening position wherein the roll 95 is disposed closely adjacent to the straightening surface 88 and cooperates therewith to clamp the adjacent portion of the strap web 40 therebetween. The free-wheeling mounting of the roll 95 permits movement of the strap web 40 between the roll 95 and the straightening surface 88 when the roll 95 is in its straightening position and operates to effect a straightening of the strap web 40 after tensioning and sealing of the strap. web 40 about the object 48, as will be described below.

Also carried by the main supportplates 44 are a plurality of side plates 96a, 97 and 98, all disposed substantially parallel to the side plate 96 and cooperating therewith to support the various components of the strapping head 55 thereon. The side plates 97 and 98 are respectively provided with lips or projections 97a and 98a at the lower ends thereof extending toward each other, for purposes to be described in detail below. The side plates 96a, 97 and98 are all interconnected by a pair of main connecting pins 99 extending through complementary openings therethrough and disposed substantially parallel to the main support plate 44 Referring now also to FIGS. 4, 7, 8, l0, l5. and'l6 of the drawings, there is provided a gripping jaw assembly, generally designated by the'numeral 100, and disposed in the gripping and tensioning section 57 of the strapping head 55. Spanning the side plates 96a, 97 and 98 and secured thereto along the bottom edges thereof, by suitable fasteners 102 are a pair of base plates 101 which are constructed as mirror images of each other and are spaced apart laterally of the strapping head 55 to' define a central passage 104 therebetween. Each of the base plates 101 is provided with a holding jaw slot 103 adjacent to the forward end thereof and a sealing jaw slot 107 at the rear end thereof, the outer side walls of the slots 103 and. 107 being respectively beveled as at 106 and 108. Secured to the base plates 101 immediately thereabove and spanning the central passage 104 therebetween isa flat backing plate 105 having a toothed bottom gripping surface 109 disposed adjacent to the holding jaw slots 103. Mounted between the side plates 96a and 97 are a pair of gripping or holding jaws.

110, respectively pivotally coupled adjacent to the upper ends thereof to a pair of pivot pins 1 13 extending between the side plates 96a and 97 and substantially normal thereto. The gripping jaws 110 are spaced apart laterally of the strapping head 55 by a predetermined distance and are each provided at'the lower end thereof with an inwardly extending projection 111 having an upwardly extending set of teeth 1 12 thereon. In use, the gripping jaws 1 are respectively disposed on opposite sides of the backing plate 105 with the projections 111 extending therebeneath and inwardly toward each other so that the teeth 112 are disposed in generally facing relationship with the tooth gripping surface 109 on the backing plate 105, as is best illustrated in FIGS. 4, 8 and 10. Each of the pivot pins 113 is secured at the opposite ends thereof, respectively, to the front leg 114 and the rear leg 116 of a generally U-shaped drive member or crosshead 115, the legs 114 and 116 being interconnected at the upper ends thereof by a bight portion 117 having a vertically elongated slot 118 extending laterally therethrough. Thus, it will be seen, that vertical movement of the crosshead 1 will effect a corresponding vertical movement of the gripping jaws 1 10 as will be described in greater detail hereinafter.

Extending between: the side plates 96a and 97 along the opposite side edges thereof, and cooperating therewith to substantially enclose the gripping and tensioning sections 57, are a pair of spacers 120, secured in position by theconnecting pins 99 which extend through complementary openingstherein. The lower end of each of the spacers l20abuts against the upper surface of the associated base plate 101, each of the spacers 120 being provided at the upper end thereof 7 with two laterally inwardly extending and vertically spaced-apart flanges 122 and 123. The flanges 122 and 123 are each provided with vertically aligned cylindrical openings 124 extending therethrough for accommodating an associated cylindrical connecting pin 125 therein. Each of the connecting pins 125 is provided at the lower end thereof with a clevis bracket 127 having downwardly extending legs and a substantially horizontal extending bight portion 128. Compression springs 129 are respectively disposed in surrounding relationship with the connecting pins 125, each of the springs 129 being retained between the adjacent flange 122 and the bight 128 of the adjacent clevis bracket 129 for resiliently urging the associated connecting pin 125 downwardly, as viewed in FIG. 10. Respectively secured to the gripping jaws 110 by means of the associated pivot pins 113 and by coupling pins 131 spaced from the pins 113 and disposed substantially parallel thereto, are two levers 130, which are in turn respectively connected by means of coupling pins 132 to the clevis brackets 127. Each lever is further provided with a lever arm 134 disposed laterally between the front and rear legs 114 and 116 of the crosshead 115 and extending beyond the opposite side edge thereof.

Disposed immediately above the crosshead 115 is a clevis block 135 having a bight portion 136 at the upper end thereof interconnecting a pair of downwardly extending legs 137, respectively disposed adjacent to the opposite ends of the crosshead slot 1 18 and receiving the crosshead bight 117 therebetween. Each of the legs 137 has a bearing surface 138 at the lower end thereof, the legs 137 also being provided with laterally aligned openings therein for accommodating a drive pin 139 therethrough, the drive pin 139 extending through the slot 118 in the cross head 115. Coupled to the bight portion 136 of the clevis block 135 by means of a coupling pin 141 extending substantially horizontally from front to rear therethrough, is a drive link 140, and drive link extending upwardly from the clevis block 135 and coupled adjacent to the upper end thereof by means of a coupling pin 143 to a lever arm 145, approximately midway between the ends thereof. The lever arm is mounted adjacent to one end thereof for pivotal movement about a pivot pin 142 disposed substantially parallel to the coupling pins 141 and 143 and secured in place between the side plates 96a and 97. The lever arm 145 is coupled adjacent to the other end thereof by means of a coupling pin 144 to the lower clevis end 147 of a coupling member 146, the member 146 having an upper clevis end 148 coupled by means of a pin 149 to the lower end of a piston rod 151 of an air-actuated piston 150. The piston is mounted on a mounting bracket 153 secured-in place between the side plates 97 and 98 by means of suitable fasteners 154.

Disposed immediately above the backing plate 105 and between the gripping jaws 110 is a bridge member 155 secured in place between the side plates 96a and 97 by means of mounting pins 156. The upper end of the bridge member 155 is provided with a flat bearing surface 157 for a purpose to be described below, and the lower end of the bridge member 155 is provided with a generally. rectangular recess 158 having dimensions slightly greater than the cross-sectional dimensions of the strap web 40 and defining a slot between the bridge member 155 and the backing plate 105 to accommodate passage of the strap web 40 therethrough.

When the piston 150 is deactuated, the gripping jaw assembly 100 will assume a home or strap-feeding configuration illustrated in the left-hand side of FIG. 10. In this feeding position, the gripping jaws 110 are pivoted toward each other with the projections 111 spaced apart a distance less than the width of the strap web 40, and with the gripping teeth 112 spaced a predetermined distance below the gripping surface 109 of the backing plate 105 to accommodate ready passage of the leading end 42 of the strap web 40 along the gripping surface 109. The gripping jaws 110 are held in this position by the action of the compression springs 129 bearing against the clevis brackets 127 and pivotally urging the levers 130 and the gripping jaws 1 10 downwardly and toward each other. The piston rod 151, the coupler 147, the lever arm 145 and the link 140 are all disposed downwardly in their lowermost positions, as indicated in broken lines in FIG. 10, with the bottom end of the crosshead 115 abutting against the bearing surface 157 on the bridge member 155. It will be noted that, in this position, the bearing surfaces 138 on the legs 137 of the clevis block 135 are disposed immediately above the lever arms 134, but out of contact therewith.

In use, when air is introduced into the bottom end of the piston 150, the piston rod 151 is moved upwardly, thereby moving the coupler 147, the lever arm 145 and the link 140 to the positions illustrated in solid line in FIG. 10. This upward movement of the drive linkage pulls the crosshead 135 upwardly so that the drive pin 139 engages the crosshead 115 along the upper edge of the slot 118, thereby pulling the crosshead 115, the levers 130 and the gripping jaws 110 vertically upwardly against the urging of the bias springs 129 to a gripping configuration illustrated in solid lines at the right-hand side of FIG. 10. In this gripping configuration, the teeth 112 of the gripping jaws 110 are disposed in firm engagement with the gripping surface 109 on the backing wall 105; or, if the leading end 42 of the strap web 40 is disposed along the gripping surface 199, the teeth 112 will securely clamp and hold the leading end 42 of the strap 40 thereagainst. This movement of the gripping jaws 110 to the gripping configuration causes a corresponding upward movement of the connecting pins 125 which is accommodated by the openings 124 in the spacer flanges 123. It will be noted that the movement of the gripping jaws 110 to this gripping configuration is such that the teeth 112 move into engagement with the adjacent portion of the strap web 4 in a direction substantially normal to the plane thereof, thereby avoiding any scraping of the teeth 112 laterally along the strap web 40 which could score and weaken the resulting strap loop.

When the air is removed from the lower end of the piston 150, the entire gripping jaw assembly 100 will be urged vertically downwardly back toward the releasing or home position thereof by the compression springs 129. It will be noted that this initial disengaging movement of the gripping jaws 110 away from the strap web 40 is in a direction substantially normal to the plane thereof, thereby to further minimize the possibility of scoring of the strap web 40. However, as a result of the tensioning of the strap about the object 48, the object 48 will be pulled up closely adjacent to or against the bottom surfaces of the gripping jaws l 10, thereby limiting downward movement thereof. Accordingly, the

compression springs 129 will operate to relieve the gripping force of the teeth 112 on the adjacent portion of the strap 40, but will be unable to move the gripping jaws 110 all the way back to their home position against the resistance of the object 48. This is particularly true where the object 48 is a relatively inflexible material, such as bricks. When air is applied to the other end of the piston 150, the piston rod 151 and the clevis block 135 are urged downwardly toward their home positions. However, before the drive pin 139 engages the crosshead 115 at the bottom of the slot 118, the bearing surfaces 138 on the clevis block legs 137 will engage the lever arms 134, thereby pivotally moving them about pivot pins 113. This pivotal movement of the levers 130 will, through the coupling pins 131, impart an outward pivotal movement to the gripping jaws 1 10, for moving the gripping jaws 110 to an open releasing position illustrated in broken lines at the right-hand side of FIG. 10, this spreading of the gripping jaws 110 being accommodated by the beveled surfaces 106 on the backing plates 101 and being limited by engagement of the drive pin 139 with the crosshead 1 15 at the bottom of the slot 118. During this outward pivotal movement, the bottom edges of the gripping jaws will slide along the adjacent surface of thepackage or object 48; After the gripping jaws 110 have arrived in the open releasing position, the projections 1 1 1 thereof will be spaced apart a distance greater than the width of the strap web 40 to accommodate removal of the sealed strap loop 65 therefrom in a downward direction, as viewed in FIG. 10. After removal of the strapped object 48, the piston will move the gripping jaws 110 downwardly until the crosshead l 15 bottoms on the bearing surface 157 of the bridge member 155, the piston 150 maintaining the gripping jaws 110 pivoted open against the urging of the springs 129. After removal of the air from the upper end of the piston 150, the gripping jaws 110 will immediately pivot back to their home or feeding configuration under the urging of the compression springs 129.

Referring now also to FIGS. 6 and 11 to 14 of the drawings, there is disposed in the sealing and shearing section 58 of the strapping head 55 a sealing jaw assembly, generally designated by the numeral 160. Disposed between the side plates 97 and 98 along the opposite side edges thereof are two identical pairs of cam plates 161, including a pair of front cam plates abuttingvagainst the rear surface of the side plate 97 and a pair of rear cam plates abutting against the front surface of the side plate 98 (see FIGS. 15 and 16). The cam plates 161 of each pair thereof are constructed as mirror images of each other, and are each provided with a curved camming surface 162 along the inner 1 1 edge thereof. The front ones of the cam plates 161 are respectively separated from the rear ones thereof by two spacers 160, the spacers 160 and cam plates 161 all being held in place by the main connecting pins 99 which extend through complementary openings therein, the cam plates 161 and spacers 160 cooperating with the side plates 97 and 98 to substantially enclose the sealing and shearing section 58. The side plate 97 is provided with a generally channel-shaped key slot 97b in the rear surface thereof for slidably receiving therein a key tab 164a of a front slide block 164. Similarly, the side plate 98 is provided with a generally channel-shaped key slot 98b in the front surface thereof for slidably receiving therein akey tab 166a of arear slide block 166; Received in a recess in the rear surface of the front slide block 164 is a shear member 165 provided at the lower end thereof with a shear blade 167. The shear member 165 has a slot centrally disposed therein extending from the front to the rear thereof for accommodating therein a coil spring 168, the coil spring 168 engaging a substantially horizontally extending pin 169 at the lower end thereof (see FIGS. 4 and 11), the front end of the pin 169 being received in a complementary opening in the front slide block 164.

Four identical pairs of sealing jaws 170 are disposed in the area bounded by the spacers 160 and the slide blocks 164 and 166. The middle two pairs of sealing jaws 170 are arranged back to back and are respectively separated from the front and rear pairs of sealing jaws 170 by two dies 175. The sealing jaws 170 of each pair thereof are constructed asmirror images of each other, each sealing jaw 170 having an arcuate lower end 171 terminating in an inwardly directed projection 171a, and being provided along the inner edge thereof with first and second recessed steps or shoulders 172 and 173 set back from the inner end of the projection 171a. Each of the dies 175 is generally rectangular in shape and is provided at the upper end thereof with a bearing surface 175a and is provided along the lower edge thereof with a crimping recess 176 having inclined side edges 176a for a purpose to be described more fully hereinafter. The opposite side edges of each of the dies 175 is provided with a recessed shoulder 177 for accommodating a return pin 178 extending from an adjacent one of the sealing jaws 170 substantially normal thereto. The sealing jaws 170 and the dies 175 are all secured together by means of a-pair of pivot pins 174 extending through complementary openings therein substantially normal thereto, the opposite ends of each of the pivot pins 174 being respectively received in complementary openings in the slide blocks 164 and 166. The two sealing jaws 170 of each pair thereof are respectively mounted for pivotal movement about the pivot pins 174, while each of the dies 175 receives both of the pivot pins 174} through elongated openings 179 I therein for accommodating vertical movement 'of the dies 175 with respect to the pivot pins 174.

Each of the sealing jaws 170 is pivotally coupled by means of coupling pins 181 to a pair of links 180, the front and rear ends of each of the coupling pins 181 extending a slight distance beyond the adjacent one of the sealing jaws 170 for rotatably mounting thereon four cam rollers 182. Each of the cam rollers 182 is disposed with the circumferential surface thereof in rolling engagement with the camming surface 162 of the adi jacent one of the cam plates 161 for guiding the movement of the sealing jaws as will be'described below.

Each of the links is connected at the other end thereof by means of coupling pins 186 to clevis slots 184 in the lower end of a crosshead 185. The crosshead 185 is pivotally connected adjacent to the upper end thereof by means of a pivot pin 186 to a lever arm 187 adjacent to one end thereof. The other end of the lever arm 187 is pivotally coupled by means of a pin 188 to an extension member 189 carried by the piston rod 191 of an air-actuated sealing piston 190. The sealing piston is mounted on the main support plate 44 by means of a mounting bracket 192 secured to the main support plate 44 by fasteners 193. The end of the lever arm 187 adjacent to the pivot pin 186 is coupled by means of a connecting pin 194 to one end of an arcuate toggle link 195, the other end of the toggle link 195 being coupled by means of apin 196 to a partial sealing lever 196, intermediate the ends thereof. One end of the partial sealing lever 197 is mounted for pivotal movement about a pivot pin 198 extending substantially horizontally between the side plates 97 and 98, the other end of the partial sealing lever 197 being coupled by means of a coupling pin 199 to an extension member 201a carried by the piston rod 102 of a partial sealing cylinder 200. The partial sealing cylinder 200 is mounted on a mounting bracket 202 which is secured to the main support plate 44 by means of suitable fasteners 203.

Disposed in a complementary slot in the front surface of the rear slide block 166 is a seal latch 205 provided with a beveled lip 206 at the lower end thereof for a purpose to be described below. The seal latch 205 has a centrally disposed recess formed therein for accommodating a latch spring 207, the upper end of the latch spring 207 bearing against the rear end of a bridge pin 209 which extends substantially horizontally between the pairs of sealing jaws 170 and through complementary openings in the dies 175, the front and rear ends of the bridge pin 209 being respectively received in complementary openings in the front and rear slide blocks 164 and 166. It will be appreciated that by reason of the interconnection thereof by the pivot pins 174 and the bridge pin 209, the slide blocks 164 and 1616, the dies 175, the shear member 165 and the seal latch 205 will all move vertically in response to vertical movement of the sealing jaws 170 between the side plates 97 and 98 In use, the sealing jaw assembly 160 is initially disposed in a retracted configuration illustrated in FIGS. 4 and 9 and in the left-hand side of FIG. 11. In this retracted configuration, air is being supplied to the bottom ends of the pistons 190 and 200, holding the piston rods 191 and 201, the levers 187 and 197 and the toggle link 195 in their uppermost positions illustrated in FIG. 9. The lever arm 187, through the crosshead 185 and the links 180 holds the sealing jaws 170 in the position illustrated in FIGS. 4 and 9, with the cam rollers 182 engaging the upper vertical portions of the cam surfaces 162 for holding the lower ends of the sealing jaws 170 spaced apart a distance greater than the width of the strap web 40. In this position, the lower ends of the sealing jaws 170 are spaced a predetermined distance vertically above the base plates 101 and cooperate therewith to define therebetween a sealing region adjacent to the overlapped portions of thestrap web 40. The dies 175 will be held out of the sealing region by means of the return pins 178 on the sealing jaws 170, while the slide blocks 164 and 166, and the seal latch 205 will be held out of the sealing region by means of the bridge pin 209, and the shear member 165 is held out of the sealing region by means of the pin 169 and compression spring 168.

When air is removed from the lower end of the piston 200 and added to the upper end thereof, the piston rod 201 will be moved downwardly, thereby pivoting the lever 197 in a counterclockwise direction about the pivot pin 198 as viewed in FIG. 9, which pivotal movement will in turn serve to move the toggle link 195 downwardly. The downward movement of the toggle link 195 will be transmitted through the pin 194 to the lever 187 and thence through the pin 186 to the crosshead 185 for effecting a downward movement thereof. It will be noted that the arrangement of the coupling pin 194 is such as to permit limited rotational movement of the toggle link 195 thereabout only in a counterclockwise direction from the uppermost position thereof illustrated in FIG.-9, whereby to transmit the initial downward movement of the toggle link 195 to the lever arm 187. The downward movement of the cross-head195 will in turn be transmitted through the links 180 to the sealing jaws 170 to effect a vertical downward movement thereof, the direction of movement of the sealing jaws 170 being limited to a vertically downward direction by the engagement of the cam rollers 182 with the vertical upper portions of the camming surfaces 162. The downward movement of the sealing jaws 170 will continue until the cam rollers 182 engage the laterally extending portions of the camming surfaces 162, at which time the cam rollers 182 will roll laterally outwardly therealong to effect a pivotal movement of the sealing jaws 170 toward each other about the pivot pins 174, as indicated in FIG. 11. The downward movement of the piston rod 201 will continue until the sealing jaws 170 have been pivoted to a partial sealing position illustrated in solid lines in the right-hand half of FIG. 11 and in FIG. 13, this pivotal movement being accommodated by the beveled surfaces 108 on the backing plates 101. At this point, the pivotal movement of the lever 197 will have moved the toggle link 195 through a slight counterclockwise pivotal movement to a locking position locking the lever 197 against further pivotal movement with respect thereto and stalling the operation of the piston 200 to limit the movement of the sealing jaws 170.

When air is now removed from the rod end of the piston 190 and applied to the head end thereof, the piston rod 191 will be moved downwardly and will, through the coupler 189, exert a downward force on the adjacent end of the lever arm 187 for pivoting the lever arm 187 in a counterclockwise direction about the axis of the coupling pin 194. It will be noted that the locked configuration of the toggle link 195 will prevent upward movement of the coupling pin 194 and consequent driving of the piston rod 201 back up into the cylinder of the piston 200. Thus, the lever arm 187 must pivot about the pin 194 rather than about the pin 186, whereby all the movement of the lever arm 187 will be transmitted through the pin 186 to the crosshead 185. Accordingly, a further downward movement will be imparted to the crosshead 185 for continuing the downward movement of the sealing members to the full-sealing position thereof, illustrated in broken line in the right-hand side of FIG. 11 and in FIG. 14, in which position the bottom ends of the sealing jaws 170 are disposed closely adjacent to each other and are spaced apart a distance substantially less than the width of the strap web 40 for sealing engagement with an associated seal 265, as will be described more fully hereinafter. After removal of air from the upper ends of the pistons 190 and 200 and reapplication thereof to the lower ends of these pistons, the piston rods 191 and 201 will be returned to their uppermost positions illustrated in FIG. 9, thereby moving the sealing jaw assembly 160 back to its retracted configuration.

It will be observed that when the sealing jaws are initially moved from their retracted configuration to the partial-sealing configuration thereof, the slide blocks 164 and 166 will be moved downwardly with the sealing jaws 170 by means of the bridge pin 209, while the shear member 165 will be moved downwardly by the action of the pin 169. However, by reason of the elongated slots 179 and 1790 therein, the dies 175 will not be moved by the bridge pin 209 and the pivot pins 174 until these pins have respectively reached the lower ends of the slots 179a and 179. This lost motion accomplishes a delayed movement of the dies 175 in response to the downward movement of the sealing jaws 170, to allow for movement of the sealing jaws 170 into their full-sealing position before the operation of the crimping dies 175. When the sealing jaws 170 have been pivoted to their fully closed or full sealing configuration, further pivotal movement thereof will be limited by the length of the links 180. However, when the sealing jaws 170 have reached this full-sealing configuration, the bottom end of the crosshead 185 will have bottomed against the bearing surface 176 on the die member 175 and against the upper end of the shear member 165. The components of the sealing body assembly are so dimensioned and arranged that the last portion of the downward movement of the crosshead 185, after movement of the sealing jaws 170 to their full-sealing positions, will be imparted solely to the dies 175 and the shear member 165. Thus, immediately after the sealing jaws have been moved to their full-sealing configuration for forming the seal joint about the overlapped portions of the strap web 40, the crimping surfaces 176a of the dies 175 will be moved into engagement with the sealed joint for crimping the opposite side edges thereof and the shear plate 167 will be moved through the supply portion of the strap web 40 immediately in front of the sealed joint for severing the sealed strap loop 51 from the supply portion of the strap web 40. It will be noted that the shearing movement of the shear member will be against the urging of the bias spring 168, whereby upon retraction of the crosshead 185, the shear member 165 will immediately spring back to its retracted position with respect to the slide block 164 of the adjacent sealing jaw as illustrated in FIG. 4. Upon retraction of the sealing jaws 170, the return pins 178 thereon will engage the shoulders 177 .of the dies for pulling the dies 175 back to the retracted positions thereof.

Mounted immediately rearwardly of the side plate 98 is a seal magazine, generally designated by the numeral 210, which includes a back plate 21 1, a front plate 121 and a pair of opposed side plates 213, all cooperating to define a hollow tube having a substantially rectangular transverse cross section with an open upper loading end and an open lower discharge end. Disposed within the seal magazine 210 is a seal follower 214 provided with a generally L-shaped lift bracket 216 extending outwardly therefrom beyond one of the side plates 213 through an elongated slot therein running substantially the length thereof. Connected to the seal follower 214 is one end of a tension cable 217, the other end of the cable 217 extending downwardly along the seal magazine 210 and around a pulley 218 disposed at the rear end thereof in an opening 219 in one of the side plates 213, and thence upwardly to a reel 215 rotatably mounted on a mounting block 215a suitably secured to the main support plate 244. The cable reel 215 is suitably biased to maintain the cable 217 under tension to urge the seal follower 214 downwardly against the upper end of a stack of seals 265 stored in the seal magazine 2111. The seals 265 are preferably of the type disclosed in the aforementioned U. S. Pat. No. 3,139,813, being generally channel-shaped with side flanges 267 extending downwardly and outwardly from the opposite side edges thereof, as viewed in FIGS. 12-14. The discharge end of the seal magazine 2111 is spaced a predetermined distance above the backing plates 101 and is disposed substantially in horizontal alignment with the lower ends of the sealing jaws 170 in the retracted positions thereof.

Disposed at the rear end of the strapping head 55 is a seal feed assembly, generally designated by the numeral 220. The seal feed assembly 220 includes a pair of slide housings 221 extending rearwardly from the rear ends of the base plates 1111, the inner surfaces of the slide housings 221 being disposed in substantially parallel vertical planes and spaced apart a predetermined distance in facing relationship with each other. The slide housings 221) are each provided with an upstanding attachment flange at the forward end thereof extending outwardly therefrom substantially normal thereto and being secured to the side plates 98 by suitable fasteners 222a. Disposed between the slide housings 221 at the rear ends thereof and secured thereto by means of a bolt 224, is an upstanding stop member 225, the bottom surface of the stop member 225 being disposed a predetermined distance above the bottom surfaces of the slide housings 221. Secured to the bottom surface of the stop member 225 is a generally T- shaped rear guide plate 226 provided with a forwardly extending tongue 227 intermediate the ends thereof, the tongue 227 terminating in a beveled distal end 228. Secured to the rear end of the guide plate 226 is a pair of guide blocks 223, suitable fasteners 223a securing together the guide blocks 223, the guide plate 226 and the stop member 225. The guide blocks 223 are spaced apart a predetermined distance slightly greater than the width of the strap web 40 and are each provided with an angled entry surface 229 for facilitating the passage of the strap web 40 therebetween.

Disposed between the slide housings 221 and slideably engaged in complementary grooves 221a in the inner surfaces thereof is a slide plate 230. immediately overlying the slide plate 231) is a connector block 231 provided at the forward end thereof with an upwardly extending projection 232. ,Also disposed between the slide housings 221 is a seal feed bar 235 substantially rectangular in transverse cross section and having the rear end thereof immediately underlying the slide plate 230 and secured thereto and to the connector block 231- by means of bolts 234. The seal feed bar 235 has a flat, substantially horizontal strap guide surface 236 along the bottom thereof, the strap guide surface 236 having a recess 233 centrally disposed in the rear end thereof for accommodating the tongue 227 of the rear guide plate 226, the strap guide surface 236 being substantially coplanar with the bottom surface of the tongue 227. The seal feed bar 235 is provided at the upper front end thereof with a recess 238 for accommodating the lower. end of the seal latch 205 in the retracted configuration thereof. Adjacent to the rear end of the recess 238 is a seal-engaging lip 239 for feeding the seals 265 from the magazine 210. It will be observed that the seal .feed bar 235 is slidably movable forwardly and rearwardly between the slide housings 221 between a seal feeding position illustrated in FIG. 4, wherein the forward end of the seal feed bar 235 is disposed in the sealing region between the open and retracted sealing jaws 270 and a retracted position, wherein the seal feed bar 235 is disposed out of the sealing region, with the seal engaging lip 239 disposed rearwardly of the front surface of the back plate 211 of the seal magazine 210.

' A seal feed piston 240 is provided for efiecting movement of the seal feed bar 235 between the feeding and retracted positions thereof, the piston 240 being mounted on an arm 241 of the mounting bracket 192. The piston 240 is provided with a piston rod 242 connected at the lower end thereof by means of a connecting pin 243 to one end of a generally L-shaped lever 245. The lever 245 is pivotally mounted intermediate the ends thereof on a pivot pin 244 carried by a mounting bracket 246 secured to the back plate 211 of the seal magazine 210. The other end of the lever 245 is coupled by means of a connecting pin 247 to one end of the link 248, the other end of the link 248 being coupled by a connecting pin249 to the projection 232 on the connector block 231. It will be appreciated that when the piston rod 242 is moved downwardly, the lever 245 will be pivoted in a counterclockwise direction, as viewed in FIG. 4, thereby pulling the seal feed bar 235 rearwardly to its retracted position, until the abutment surface 237 at the rear end of the seal feed bar 235 abuts against the stop member 225. Similarly, when the piston rod 242 is moved upwardly, the lever 245 will be pivoted in a clockwise direction, thereby pushing the seal feed bar 235 forwardly to its feeding position.

it will be noted that when the seal feed bar 235 is in its withdrawn position, the bottommost one of the seals 265 in the seal magazine 2110 will be urged by the seal follower 214 downwardly against the upper surface of the seal feed bar 235 immediately in front of the seal engaging lip 239. Accordingly, when the seal feed bar 235 moves forwardly to its feeding position, the seal engaging lip 239 engages the adjacent seal 265 and carries it forwardly to a holding position between the open retracted sealing jaws 270. As the seal 265 moves forwardly, it engages the beveled lower edge 206 of the seal latch 205 andmoves the seal latch 2115 rearwardly 

1. A strapping machine for applying a length of strap around an object, said strapping machine comprising first and second gripping members having gripping surfaces thereon and being movable between a feeding condition and a gripping condition, said gripping members in the feeding condition thereof being spaced apart for accommodating the free passage of the leading end of the strap therebetween for forming a loop around the object with the leading end of the strap overlapping the supply portion thereof, said gripping members in the gripping condition thereof cooperating for securely clamping the leading end of the strap therebetween with said gripping surfaces respectively in engagement with the opposite sides of the leading end of the strap, drive mechanism coupled to said gripping members for effecting movement thereof between the feeding condition and the gripping condition thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, and joint forming means for forming a joint between the overlapped portions of the tensioned strap to secure the strap about the object, said drive mechanism effecting movement of said gripping members only in a direction substantially normal to the plane of the adjacent portion of the strap just prior to contact therewith to prevent scoring thereof by said gripping surfaces and to prevent relative movement between said gripping members and the strap in a direction longitudinally of the strap, whereby said gripping members securely hold the leading end of the strap without scoring and resultant weakening thereof.
 2. The strapping machine set forth in claim 1, wherein each of said gripping surfaces is provided with a plurality of teeth thereon, the teeth on one of said gripping surfaces being shaped complementary to the teeth on the other of said gripping surfaces.
 3. The strapping machine set forth in claim 1, wherein said drive mechanism effects movement of said gripping members from the feeding condition thereof to the gripping condition thereof in a direction substantially normal to the plane of the adjacent portion of the strap.
 4. The strapping machine set forth in claim 1, wherein one of said gripping members is stationary, the other of said gripping members being movable with respect to said one gripping member between the feeding condition and the gripping condition.
 5. A strapping machine for applying a length of strap around an object, said strapping machine comprising a first gripping member having a gripping surface thereon, a second gripping member having teeth thereon and being movable among a strap feeding condition and a gripping condition and a releasing condition, said second gripping member in the feeding condition thereof being spaced from said gripping surface for accommodating free passage of the leading end of the strap therebetween to form a loop around the object with the leading end of the strap overlapping the supply portion thereof, said second gripping member in the gripping condition thereof cooperating with said first gripping member for securely clamping the leading end of the strap therebetween with said teeth and said gripping surface respectively firmly engaging the opposite sides of the leading end of the strap, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, and joint forming means for forming a joint between the overlapped portions of the tensioned strap to secure the strap about the object, said second gripping member in the releasing condition thereof being disposed out of engagement with the strap loop to accommodate release thereof from between said gripping members, and drive mechanism coupled to said second gripping member for effecting movement thereof among the feeding condition and the gripping Condition and the releasing condition thereof, said drive mechanism effecting movement of said second gripping member only in a first direction substantially normal to the plane of the adjacent portion of the strap just prior to contact therewith to prevent scoring thereof by said teeth, said drive mechanism effecting initial movement of said second gripping member away from the gripping condition thereof only in a second direction opposite to said first direction to further prevent scoring of the strap by said teeth and to prevent relative movement between said gripping members and the strap in a direction longitudinally of the strap, whereby said gripping members alternately hold and release the leading end of the strap without scoring and resultant weakening thereof.
 6. The strapping machine set forth in claim 5, and further including a pair of second gripping members each having teeth thereon and being movable among said strap feeding and gripping and releasing conditions.
 7. The strapping machine set forth in claim 5, wherein said second gripping member in the releasing condition thereof abuts against the object, whereby the object limits the movement of said second gripping member in said second direction.
 8. The strapping machine set forth in claim 5, wherein said first gripping member is provided with teeth thereon shaped complementary to the teeth on said second gripping member.
 9. The strapping machine set forth in claim 5, and further including control apparatus coupled to said drive mechanism for controlling the operation thereof to move said second gripping member from the feeding condition thereof to the gripping condition thereof just prior to operation of said tensioning means and to said second gripping member from the gripping condition thereof to the releasing condition thereof after operation of said joint forming means.
 10. A strapping machine for applying a length of strap around an object, said strapping machine comprising a first gripping member having a gripping surface thereon, a second gripping member having teeth thereon and being movable among a feeding condition and a gripping condition and first and second releasing conditions, said second gripping member in the feeding condition thereof being spaced from said gripping surface for accommodating free passage of the leading end of the strap therebetween to form a loop around the object with the leading end of the strap overlapping the supply portion thereof, said second gripping member in the gripping condition thereof cooperating with said first gripping member for securely clamping the leading end of the strap therebetween with said teeth and said gripping surface respectively firmly engaging the opposite sides of the leading end of the strap, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, joint forming means for forming a joint between the overlapped portions of the strap to secure the strap about the object, said second gripping member in the first releasing condition thereof being disposed intermediate the feeding condition and the gripping condition thereof and abutting against the strapped object, said second gripping member in the second releasing condition thereof abutting the strapped object laterally of the strap and out of engagement therewith for accommodating release of the sealed strap from said gripping members, and drive mechanism coupled to said second gripping member for effecting movement thereof among the feeding condition and the gripping condition and the first and second releasing conditions thereof, said drive mechanism effecting movement of said second gripping member in a predetermined direction substantially normal to the plane of the adjacent portion of the strap just prior to contact therewith to prevent scoring thereof by said teeth, said drive mechanism effecting initial movement of said second gripping member away from the gripping condition thereof in a direction oppOsite to said predetermined direction to further prevent scoring of the strap by said teeth, said drive mechanism effecting pivotal movement of said second gripping member from the first releasing condition to the second releasing condition thereof along the strapped object, whereby said gripping members alternately hold and release the leading end of the strap without scoring and resultant weakening thereof.
 11. The strapping machine set forth in claim 10, and further including a pair of second gripping members each having teeth thereon and being movable among said strap feeding and gripping and releasing conditions.
 12. The strapping machine set forth in claim 10, wherein said drive mechanism effects pivotal movement of said gripping member from the first releasing condition to the second releasing condition thereof about an axis disposed substantially parallel to the plane of the adjacent portion of the strap.
 13. A strapping machine for applying a length of strap around an object, said strapping machine comprising a first gripping member having a gripping surface thereon, a second gripping member having teeth thereon and being movable among a feeding condition and a gripping condition and first and second releasing conditions, said second gripping member in the feeding condition thereof being spaced from said gripping surface for accommodating free passage of the leading end of the strap therebetween to form a loop around the object with the leading end of the strap overlapping the supply portion thereof, said second gripping member in the gripping condition thereof cooperating with said first gripping member for securely clamping the leading end of the strap therebetween with said teeth and said gripping surface respectively firmly engaging the opposite sides of the leading end of the strap, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, joint forming means for forming a joint between the overlapped portions of the strap to secure the strap about the object, said second gripping member in the first releasing condition thereof being disposed intermediate the feeding condition and the gripping condition thereof and abutting against the strapped object, said second gripping member in the second releasing condition thereof abutting the strapped object laterally of the strap and out of engagement therewith for accommodating release of the sealed strap from said gripping members, bias means urging said second gripping member toward the feeding condition thereof, and a drive assembly coupled to said second gripping member and operable to first and second actuated conditions and cooperating with said bias means for effecting movement of said second gripping member among the feeding condition and the gripping condition and the first and second releasing conditions thereof, said drive assembly in the first actuated condition thereof effecting movement of said second gripping member in a predetermined direction substantially normal to the plane of the adjacent portion of the strap just prior to contact therewith to prevent scoring thereof by said teeth, said bias means and said drive assembly in the second actuated condition thereof effecting initial movement of said second gripping member away from the gripping condition thereof in a direction opposite to said predetermined direction to further prevent scoring of the strap by said teeth, said drive assembly in the second actuated condition thereof cooperating with said object for effecting pivotal movement of said second gripping member from the first releasing condition thereof to the second releasing condition thereof along the strapped object, said bias means effecting movement of said second gripping member back to the feeding condition thereof upon deactuation of said drive assembly after removal of the strapped object therefrom, whereby said gripping members alternately hold and release the leading end of the strap without scoring and resultAnt weakening thereof.
 14. The strapping machine set forth in claim 13, wherein said drive assembly includes an air motor and a drive linkage coupling said air motor to said second gripping member.
 15. The strapping machine set forth in claim 13, wherein said bias means comprises a spring.
 16. The strapping machine set forth in claim 13, wherein said drive assembly includes an air motor operable to the first and second actuated conditions, drive linkage coupling said air motor to said second gripping member for effecting movement thereof, and a lever arm coupled to said second gripping member and movable therewith, said air motor in the first actuated condition thereof cooperating with said drive linkage for effecting movement of said second gripping member to the gripping condition thereof, said air motor in the second actuated condition thereof effecting movement of said drive linkage into engagement with said lever arm when said second gripping member is in the first releasing condition thereof for pivotally moving said second gripping member to the second releasing condition thereof.
 17. The strapping machine set forth in claim 13, wherein said second gripping member is pivotally movable about an axis disposed substantially parallel to the plane of the adjacent portion of the strap.
 18. The strapping machine set forth in claim 13, wherein said second gripping member is pivotally movable about an axis disposed substantially parallel to the plane of the adjacent portion of the strap, said axis passing through said second gripping member and being movable therewith.
 19. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portions of the strap for holding a seal therein and a withdrawn position out of said sealing region, sealing jaws movable between a sealing position in said sealing region for deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of said sealing region, and drive mechanism coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, said drive mechanism being coupled to said sealing jaws for effecting movement thereof between the sealing position and the retracted position thereof, said drive mechanism alternately placing said seal feed member and said sealing jaws in the sealing region without interference one with the other, whereby said seal feed member and said sealing jaws cooperate to place a seal in sealing engagement with the overlapped portions of the strap to form the seal joint therebetween.
 20. The strapping machine set forth in claim 19, wherein said seal feed member is provided with a guide surface thereon, said guide surface guiding the passage of the leading end of the strap through said sealing region when said seal feed member is in the feeding position thereof.
 21. The strapping machine set forth in claim 19, wherein said drive mechanism includes a first air motor coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, a second air motor coupled to said sealing jaws for effecting movement thereof between the sealing position and the retracted position thereof, and control apparatus coupled to said first and second air motors for controlling the operation thereof to alternately place said seal feed member and said sealing jaws in the sealing region.
 22. The strapping machine set forth in claim 19, wherein movement of said seal feed member from the withdrawn position thereof to the Feeding position thereof effects movement of a seal from a supply thereof to a holding location in said sealing region adjacent to said sealing jaws in the retracted position thereof, movement of said sealing jaws from the retracted position thereof to the sealing position thereof effecting movement of the seal from said holding location into sealing engagement with the overlapped portions of the strap.
 23. The strapping machine set forth in claim 19, wherein said sealing jaws include a plurality of pairs of jaws aligned longitudinally of the overlapped portions of the strap substantially parallel to one another and having a combined longitudinal extent substantially equal to the length of the associated seal.
 24. The strapping machine set forth in claim 19, and further including a cutter coupled to said sealing jaws and movable therewith for severing the sealed strap loop from the supply portion of the strap immediately after formation of the seal joint.
 25. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portion of the strap for holding a seal therein and a withdrawn position out of said sealing region, sealing jaws movable between a sealing position in said sealing region for deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of said sealing region, said sealing jaws having camming surfaces thereon and being spaced apart a distance greater than the width of the seal, cam members respectively disposed for camming engagement with the camming surfaces of said sealing jaws, and drive mechanism coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, said drive mechanism being coupled to said sealing jaws for effecting movement thereof between the sealing position and the retracted position thereof, said drive mechanism alternately placing said seal feed member and said sealing jaws in the sealing region without interference one with the other, said camming surfaces cooperating with said cam members and said drive means for effecting movement of said sealing jaws into said sealing region in a direction substantially normal to the plane of the adjacent portion of the strap during the first portion of the movement of said sealing jaws from the retracted position thereof to the sealing position thereof, said camming surfaces cooperating with said cam members and said drive means for effecting pivotal movement of said sealing jaws into engagement with the side edges of the seal for forming the seal joint during the last portion of the movement of said sealing jaws from the retracted position thereof to the sealing position thereof, whereby said seal feed member and said sealing jaws cooperate to place a seal in sealing engagement with the overlapped portions of the strap to form the seal joint therebetween.
 26. The strapping machine set forth in claim 25, wherein said drive mechanism includes a first air motor coupled to said seal feed member for effecting movement thereof between the feeding and withdrawn positions thereof, a second air motor coupled to said sealing jaws for effecting movement thereof between the sealing and retracted positions thereof, and control apparatus coupled to said first and second air motors for controlling the operation thereof to alternately place said seal feed member and said sealing jaws in the sealing region.
 27. The strapping machine set forth in claim 25, wherein said sealing jaws are respectively pivotally movable about axes disposed substantially parallel to the plaNe of the adjacent portion of the strap.
 28. The strapping machine set forth in claim 25, wherein said sealing jaws are respectively pivotally movable about axes disposed substantially parallel to the plane of the adjacent portion of the strap, each of said axes passing through the associated sealing jaw and being movable therewith.
 29. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portion of the strap for holding a seal therein and a withdrawn position out of said sealing region, sealing jaws movable between a sealing position in said sealing region for deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of said sealing region, said sealing jaws having camming surfaces thereon and being spaced apart a distance greater than the width of the seal, cam members respectively disposed for camming engagement with the camming surfaces of said sealing jaws, first drive mechanism coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, second drive mechanism coupled to said sealing jaws for effecting movement thereof between the sealing position and the retracted position thereof, said camming surfaces cooperating with said cam members and said drive means for effecting movement of said sealing jaws into said sealing region in a direction substantially normal to the plane of the adjacent portion of the strap during the first portion of the movement of said sealing jaws from the retracted position to the sealing position thereof, said camming surfaces cooperating with said cam members and said second drive means for effecting pivotal movement of said sealing jaws into engagement with the side edges of the seal for forming the seal joint during the last portion of the movement of said sealing jaws from the retracted position to the sealing position thereof, and control apparatus coupled to said first and second drive mechanisms for controlling the operation thereof to alternately place said seal feed member and said sealing jaws in the sealing region without interference one with the other, whereby said seal feed member and said sealing jaws cooperate to place a seal in sealing engagement with the overlapped portions of the strap to form the seal joint therebetween.
 30. The strapping machine set forth in claim 29, wherein each of said drive mechanisms comprises an air motor.
 31. The strapping machine set forth in claim 29, wherein each of said drive mechanisms comprises an air motor, said control apparatus comprising an electric control circuit and a pneumatic control circuit coupling said electric control circuit to said air motors.
 32. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portion of the strap for holding a seal therein and a withdrawn position out of said sealing region, sealing jaws movable among a partial sealing position and a full sealing position in said sealing region for sequentially deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of said sealing region, said sealing jaws having camming surfaces thereon and being spaced apart a distance greater than the width of the seal, cam members respectively disposed for camming engagement with the camming surfaces of said sealing jaws, and first drive mechanism coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, second drive mechanism coupled to said sealing jaws for effecting movement thereof between the retracted position and the partial sealing position thereof, third drive mechanism coupled to said sealing jaws for effecting movement thereof between the partial sealing position and the full sealing position thereof, said camming surfaces cooperating with said cam members and said second drive mechanism for effecting movement of said sealing jaws into said sealing region in a direction substantially normal to the plane of the adjacent portion of the strap during the first portion of the movement of said sealing jaws from the retracted position to the partial sealing position thereof, said camming surfaces cooperating with said cam members and said second drive mechanism for effecting pivotal movement of said sealing jaws into engagement with the side edges of the seal during the last portion of the movement of said sealing jaws from the retracted position to the sealing position thereof for deforming the seal into a configuration loosely enveloping the overlapped portions of the strap to accommodate tensioning thereof, said camming surfaces cooperating with said cam members and said third drive mechanism for effecting continued pivotal movement of said sealing jaws from the partial sealing position to the full sealing position thereof for forming the seal joint, and control apparatus coupled to said first and second and third drive mechanisms for controlling the operation thereof to alternately place said seal feed member and said sealing jaws in the sealing region without interference one with the other, said control apparatus controlling the operation of said second and third drive mechanisms for moving said sealing jaws into the partial sealing position thereof prior to operation of said tensioning means and for moving said sealing jaws from the partial sealing position to the full sealing position thereof after operation of said tensioning means, whereby said seal feed member and said sealing jaws cooperate to place a seal in sealing engagement with the overlapped portions of the strap to form the seal joint therebetween.
 33. The strapping machine set forth in claim 32, wherein each of said drive mechanisms comprises an air motor.
 34. The strapping machine set forth in claim 32, wherein movement of said seal feed member from the withdrawn position thereof to the feeding position thereof effects movement of a seal from a supply thereof to a holding location in said sealing region adjacent to said sealing jaws in the retracted position thereof, movement of said sealing jaws from the retracted position thereof to the sealing position thereof effecting movement of the seal from said holding location into sealing engagement with the overlapped portions of the strap.
 35. The strapping machine set forth in claim 32, wherein said sealing jaws in the partial sealing position thereof cooperate to deform the associated seal into a configuration loosely enveloping the overlapping portions of the strap for preventing displacement thereof from the sealing region while accommodating tensioning of the strap.
 36. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap by withdrawing the supply portion thereof relative to the leading end thereof, a seal feed member movable between a feeding position in a sealing region adjacent to the overlapped portion of the strap for holding a seal therein and a withdrawn position out of said sealing region, sealing jaws movable between a sealing position in said sealing region for deforming the seal around the overlapped portions of the strap to form a seal joint therebetween and a retracted position out of said sealing region, a die member movable between a sealing position in said sealing region for crimping the side edges of the seal and the strap for facilitating the formation of the seal joint therebetween and a retracted position out of the sealing region, and drive mechanism coupled to said seal feed member for effecting movement thereof between the feeding position and the withdrawn position thereof, said drive mechanism being coupled to said sealing jaws and said die member for effecting movement thereof between the sealing positions and the retracted positions thereof, said drive mechanism simultaneously placing said sealing jaws and said die member in the sealing region for formation of the seal joint, said drive mechanism placing said seal feed member in the sealing region alternately with the simultaneous placement of the sealing jaws and die member therein without interference of the seal feed member with the sealing jaws and the die member, whereby said seal feed member and said sealing jaws and said die member cooperate to place a seal in sealing engagement with the overlapped portions of the strap to form the seal joint therebetween.
 37. The strapping machine set forth in claim 36, wherein said die member is coupled to said sealing jaws and is movable therewith into crimping engagement with the associated seal.
 38. The strapping machine set forth in claim 36, wherein said sealing jaws include a plurality of pairs of sealing jaws, and further including a plurality of die members respectively disposed between adjacent pairs of said sealing jaws, and means coupling said die members to said sealing jaws for movement therewith.
 39. The strapping machine set forth in claim 36, wherein said die member is coupled to said sealing jaws for movement therewith, and further including a cutter coupled to said sealing jaws and said die member for movement therewith to sever the seal strap loop from the supply portion of the strap immediately after formation of the seal joint. 